1. Field
This invention relates to a multilayer data carrier, in particular an identification card or the like, which bears a difficult-to-forge security element which is detectable by simple means.
2. Related Art
From WO 2005/048182 A1 there is known a generic data carrier which is based on a transparent foil on which there are formed on a viewing front side in this order: a fluorescent printed layer applied by printing technology, a first foil-shaped metallic layer, a foil-shaped transparent interlayer, and a second foil-shaped metallic layer with a different ground color. The two metallic layers have recesses which are formed by means of a laser and form a marking present in the two metallic layers in exact register. The marking may be in particular a portrait. On account of the different ground colors of the two metal layers, the marking appears different upon viewing of the data carrier from the front compared to viewing from the back. Upon viewing of the data carrier from the front and simultaneous illumination of the back by UV radiation, the gaps further appear as fluorescent places.
In a variant it is further proposed to employ, instead of a transparent base foil with a printed fluorescent layer, a central carrier foil doped with fluorescent pigments having applied thereto on each side a layer sequence consisting of two vapor-deposited metallic layers and one intermediate transparent layer. The altogether four vapor-deposited metallic layers again have recesses formed therein by means of a laser which form an exactly registered marking in all four layers. Upon illumination of the central carrier foil by suitable excitation radiation, the marking appears fluorescent.
The known solution provides a difficult-to-imitate authenticity feature by making it possible to check with the naked eye the layer structure of a data carrier—namely by the presence of at least two spaced, marked layers—and the quality of the marking—by its register accuracy. However, the known solution presupposes that the two sides of the data carrier are configured so as to be coordinated with each other, thereby limiting the free designability of one surface of the data carrier. The surface space for applying other security features or identifying features is accordingly lost.
From WO 2005/053968 there is further known the proposal of forming markings in the form of patterns, letters, numbers and/or images by means of a laser in a security element having a metal layer disposed between two translucent cover layers. The markings in the metal layer show a watermark effect by which they appear in a positive representation upon viewing in transmitted light and in a negative representation upon viewing in reflected light. This solution presupposes that the security element can be viewed from two sides.